Functionalized high cis-1,4-polybutadiene prepared using novel functionalizing agents

ABSTRACT

A method for preparing a functionalized polymer comprising the steps of preparing a polymer by polymerizing conjugated diene monomer with a lanthanide-based catalyst, wherein the lanthanide-based catalyst comprises (a) a lanthanide compound, (b) an alkylating agent, and (c) a source of halogen, and reacting the pseudo-living polymer with at least one amide-containing functionalizing agent.

This application is a continuation of U.S. application Ser. No.11/216,559, filed Aug. 31, 2005, which is a continuation of U.S.application Ser. No. 10/381,829, filed Sep. 22, 2003, which claimspriority from International Application No. PCT/US00/30969, filed onNov. 10, 2000, all of which are incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to functionalizing agents, functionalizedpolymers prepared by contacting at least one functionalizing agent witha pseudo-living polymer, and processes for functionalizing thesepolymers. The functionalizing agents are generally defined by theformula A-R¹—Z, where A is a substituent that will undergo an additionreaction with a pseudo-living polymer, R¹ is a divalent organic group,and Z is a substituent that will react or interact with organic orinorganic fillers.

BACKGROUND OF THE INVENTION

Conjugated diene polymers are commonly used in the rubber industry.These polymers are often prepared by using coordination-catalysistechniques because the microstructure of the resulting polymer can becontrolled. Polybutadiene having greater than 90 percent of its units inthe 1,4-cis configuration can be produced with a coordination catalystsystem that includes a nickel, cobalt, or titanium compound, analkylating agent, and a halogen source. Polymers having thismicrostructure have a low glass transition temperature (T_(g)), whichprovides good low-temperature properties. Also, high 1,4-cis polymershave excellent wear resistance and mechanical properties such as reducedcut growth.

The tire industry has been challenged to design tires that have improvedrolling resistance, which contributes to better fuel efficiency.Attempts to improve rolling resistance have included alternate tiredesigns and the use of rubber that has less hysteresis loss. Also, therehas been a trend toward the use of silica as a reinforcing filler.Polymers that interact with the reinforcing fillers of tires havedemonstrated less hysteresis loss.

Functionalized polymers prepared with anionic polymerization techniqueshave demonstrated lower hysteresis loss. They can be functionalized bothat initiation and termination. Polybutadiene has been produced byinitiating polymerization of 1,3-butadiene with functionalizedinitiators to provide polymers that have a greater affinity towardcarbon black or silica filler. Anionically polymerized polymers havealso been terminated with functionalized terminators to provide polymersthat have a greater affinity toward carbon black or silica fillers.Unfortunately because anionic polymerization does not provide strictcontrol over the polymer microstructure, high 1,4-cis polymers are notobtained.

Coordination catalysis limits the ability to functionalize the resultingpolymers because they operate by chemical mechanisms that involve theinteraction of several chemical constituents, and often also involveself-termination reactions. As a result, the reaction conditionsrequired to achieve functionalization are difficult to obtain.

Terminating agents, such as organo metal halides, heterocumulenecompounds, three-membered heterocyclic compounds, and certain otherhalogen containing compounds, will react with polymers prepared with alanthanide-based catalyst system. The resulting functionalized polymers,however, do not have a useful enough affinity toward either silica orcarbon black fillers.

Therefore, there is a need in the art to provide functionalizing agentsthat will react with polymers prepared with coordination catalysts toyield functionalized polymers having a high cis microstructure and anaffinity toward carbon black and silica.

SUMMARY OF INVENTION

In general the present invention provides a method for preparing afunctionalized polymer comprising the steps of preparing a polymer bypolymerizing conjugated diene monomer with a lanthanide-based catalyst,wherein the lanthanide-based catalyst comprises (a) a lanthanidecompound, (b) an alkylating agent, and (c) a source of halogen, andreacting the pseudo-living polymer with at least one functionalizingagent selected from the group consisting of:

where R¹ is a divalent bond or divalent organic group comprising from 0to about 20 carbon atoms, R² is a divalent organic group or trivalentorganic group in the case where R² combines with R⁴ to form a cyclicgroup, each R⁴ is independently a hydrogen atom, a monovalent organicgroup, or, in the case where R⁴ combines with R¹, R², or another R⁴, R⁴may be a divalent organic group, and Z is selected from the groupconsisting of N,N-disubstituted aminophenyl groups, cyclic amino groups,imine groups, amide groups, isocyanate groups, isothiocyanate groups,and epoxy groups, with the proviso that R¹, R², R⁴ and Z aresubstituents that will not protonate a pseudo-living polymer.

Advantageously, the functionalizing agents of the present invention willreact with a pseudo-living polymer to form an end-functionalizedpolymer, while not protonating the pseudo-living polymer. Thisreactivity, among other things, allows functionalized pseudo-livingpolymers to be prepared by a process comprising contacting one or morefunctionalizing agents, including mixtures thereof, with a pseudo-livingpolymer. Further, the functionalized polymer so formed contains asubstituent which will react or interact with fillers and thereby reducehysteresis loss. Furthermore, the process of the present invention canbe used to functionalize high cis-1,4-polymers, resulting infunctionalized polymers with low glass transition temperatures and goodlow-temperature properties. In addition, the functionalized polymers ofthe present invention can advantageously be used in the manufacture ofvarious tire components including, but not limited to, tire treads, sidewalls, subtreads, and bead fillers.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The polymers that are functionalized are prepared from lanthanide-basedcoordination catalyst systems. These polymers are preferablycharacterized in that greater than about 85% of the polymer is in thecis microstructure, less than about 3% of the polymer is in the 1,2 or3,4 microstructure, and molecular weight distribution of the polymer isless than about 4. Because these polymers have been found to demonstratesome living characteristics, they may be called pseudo-living polymerswithin this specification.

This invention is not limited to functionalizing a polymer prepared fromany particular lanthanide-based catalyst. One useful catalyst includes alanthanide compound, an alkylating agent, and a source of halogen. Thelanthanide compound can include neodymium (Nd) carboxylates including Ndneodecanoate. Also, the lanthanide compound can include the reactionproduct of a Nd carboxylate and a Lewis base such as acetylacetone. Thealkylating agents can generally be defined by the formula AlR₃, whereeach R, which may be the same or different, is hydrogen, a hydrocarbylgroup, or an alkyl aluminoxy group, with the proviso that at least one Ris a hydrocarbyl group. Examples of these alkylating agents include, butare not limited to, trialkyl aluminum, dialkyl aluminum hydride, alkylaluminum dihydride, and mixtures thereof. Examples of alkylating agentswhere R is an alkyl aluminoxy group include methyl aluminoxanes. Sourcesof halogen can include organoaluminum chloride compounds. Catalystsystems that generally include lanthanide compounds and alkylatingagents definable by the formula AlR³ are disclosed in U.S. Pat. Nos.3,297,667, 3,541,063, and 3,794,604, which are incorporated herein byreference.

One particularly preferred catalyst includes (a) the reaction product ofNd carboxylate and acetylacetone, (b) triisobutylaluminum,diisobutylaluminum hydride, isobutylaluminum dihydride, or a mixturethereof, and (c) diethylaluminum chloride, ethylaluminum dichloride, ormixtures thereof. This catalyst system is disclosed in U.S. Pat. No.4,461,883, which is incorporated herein by reference. Another preferredcatalyst includes (a) Nd neodecanoate, (b) triisobutylaluminum,diisobutylaluminum hydride, isobutylaluminum dihydride, or a mixturethereof, and (c) diethylaluminum chloride, ethylaluminum dichloride, ormixtures thereof. This catalyst system is disclosed in Can. Pat. No.1,223,396, which is incorporated herein by reference.

Typically, from about 0.0001 to about 1.0 mmol of lanthanide metal areemployed per 100 grams of monomer. More preferably, from about 0.001 toabout 0.75, and even more preferably from about 0.005 to about 0.5 mmolof lanthanide metal per 100 grams of monomer are employed. The ratio ofalkylating agent to lanthanide metal is from about 1:1 to about 1:500,more preferably from about 3:1 to about 250:1, and even more preferablyfrom about 5:1 to about 200:1. The ratio of halogen source to lanthanidemetal is from about 0.1:1 to about 30:1, more preferably from about0.2:1 to about 15:1, and even more preferably from about 1:1 to about10:1.

Monomers that are polymerized by the lanthanide-based catalysts areconjugated diene monomers that include, but are not limited to,1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, andmyrcene. 1,3-butadiene is most preferred. These conjugated dienes may beused either alone or in combination. If desired, a small amount ofmonomer other than conjugated dienes can be added. These other monomersinclude, but are not limited to, aromatic vinyl compounds such asstyrene. The amount of the copolymerizable monomer is not limited, butis usually less than 10 percent by weight (pbw) preferably less than 5pbw, and even more preferably less than about 3 pbw of the entirepolymer.

Useful functionalizing agents include those generally defined by theformula (I)A-R¹—Z  (I)where A is a substituent that will undergo an addition reaction with apseudo-living polymer, R¹ is a divalent bond or divalent organic group,and Z is a substituent that will react or interact with organic orinorganic filler, with the proviso that A, R¹, and Z are substituentsthat will not protonate a pseudo-living polymer. Substituents that willnot protonate a pseudo-living polymer refer to those substituents thatwill not donate a proton to the polymer by way of a protolysis reaction.

Substituents that will undergo an addition reaction with a pseudo-livingpolymer, and are thus useful as substituent A of the above formula,include ketone, aldehyde, amide, ester and imidazolidinone groups,isocyanate, and isothiocyanate groups. The amide groups includeisocyanulate groups.

Substituents that will react or interact with organic or inorganicfiller, and are thus useful as substituent Z of the above formulainclude N,N-disubstituted aminophenyl, imine, cyclic amino, epoxy,isocyanate, isothiocyanate, and amide groups.

A divalent organic group includes a hydrocarbylene group that containsfrom 0 to about 20 carbon atoms. More preferably, the hydrocarbylenegroup contains from about 1 to about 10 carbon atoms, and even morepreferably from about 2 to about 8 carbon atoms. In the case where thehydrocarbylene group contains 0 carbon atoms, the group simplyrepresents a single bond between the group Z and the group A. Suitablehydrocarbylene groups include, but are not limited to, alkylene,cycloalkylene, substituted alkylene, substituted cycloalkylene,alkenylene, cycloalkenylene, substituted alkenylene, substitutedcycloakenylene, arylene, and substituted arylene. The term “substituted”refers to an organic group, such as a hydrocarbyl group, that replaces ahydrogen atom attached to a carbon within the group. The hydrocarbylenegroup may contain hetero atoms such as nitrogen (N), oxygen (O), sulfur(S), phosphorus (P), and silicon (Si). Hydrocarbylene groups thatinclude O may be referred to as oxo-hydrocarbylene groups, or, wherethey include N, as aza-hydrocarbyl-hydrocarbylene groups.

Some specific examples of hydrocarbylene groups include methylene,ethylene, 1,3-propylene, 1,2-propylene, 1,4-butylene,1,4-(2-methyebutylene, 1,5-pentylene, cyclopentylene, and phenylene.

In one embodiment, where A contains a ketone or aldehyde group, thefunctionalizing agents can be defined by the formula (II)

where R¹ and Z are as defined above, R² is a divalent organic group or atrivalent organic group in the case where R² combines with R³ to form acyclic group, and R³ is a hydrogen atom, a monovalent organic group, or,in the case where R³ combines with R², R³ may be a divalent organicgroup.

A monovalent organic group includes hydrocarbyl groups that contain from1 to about 20 carbon atoms. More preferably, these groups will includefrom about 2 to about 10 carbon atoms, and even more preferably fromabout 3 to about 8 carbon atoms. These hydrocarbyl groups can include,but are not limited to, alkyl, cycloalkyl, substituted alkyl,substituted cycloalkyl, alkenyl, cycloalkenyl, substituted alkenyl,substituted cycloalkenyl, aryl, substituted aryl, allyl, aralkyl,alkaryl, and alkynyl groups, and may contain hetero atoms such as N, O,S, P, and Si. Where these hydrocarbyl groups include 0, they may bereferred to as oxo-hydrocarbyl groups, or where they include N, they maybe referred to as aza-hydrocarbyl-hydrocarbyl groups.

Specific examples of hydrocarbyl groups include methyl, ethyl, propyl,isopropyl, butyl, 2-methylbutyl, pentyl, hexyl, cyclohexyl, heptyl,octyl, cyclo-octyl, 2-ethylhexyl, and 2-propylhexyl.

Where R³ is an organic group, the substituent A contains a ketone group.Non-limiting examples of ketone groups include benzophenone, andacetophenone. Non-limiting examples of ketone-containing functionalizingagents definable by the formula (II) include4,4′-bis(N,N-dimethylamino)benzophenone,4,4′-bis(N,N-diethylamino)benzophenone,4-(N,N-dimethylamino)benzophenone, 4-(N,N-diethylamino)benzophenone,(4-N,N-dimethylaminophenyl)methyl ethyl ketone,4,4′-bis(1-hexamethyleneiminomethyl)benzophenone,4,4′-bis(1-pyrrolidinomethyl)benzophenone,4-(1-hexamethyleneiminomethyl)benzophenone,4-(1-pyrrolidinomethyl)benzophenone, and(4-(1-hexamethyleneimino)phenyl)methyl ethyl ketone.

Where R³ is a hydrogen atom, the substituent A contains an aldehydegroup. A non-limiting example of a reactive aldehyde group includesbenzalaldehyde group. Non-limiting examples of aldehyde-containingfunctionalizing agents include 4-(N,N-dimethylamino)benzaldehyde,4-(N,N-diethylamino)benzaldehyde,4-(1-hexamethyleneiminomethyl)benzaldehyde, and4-(1-pyrrolidinomethyl)benzaldehyde.

One particularly preferred class of ketone-containing functionalizingagents include those compounds where Z is an N,N-disubstitutedaminophenyl group. These functionalizing agents have surprisingly beenfound to be extremely useful for functionalizing pseudo-living polymersthat have been prepared with lanthanide-based catalyst systems thatemploy trialkyl aluminum, dialkyl aluminum hydride, alkyl aluminumhydride, or alkyl aluminoxane alkylating agents or any combination ofthese, and a source of halide. This finding is advantageous because thepseudo-living polymers may be prepared in the absence ofphosphorous-containing compounds, and without any particular need toprepare the catalyst by a specific process.

One particularly preferred class of aldehyde-containing functionalizingagents include those compounds where Z is an N,N-disubstitutedaminophenyl group. These functionalizing agents have surprisingly beenfound to be extremely useful for functionalizing pseudo-living polymersthat have been prepared with lanthanide-based catalyst systems thatemploy trialkyl aluminum, dialkyl aluminum hydride, or alkyl aluminumhydride, or any combination of these, and a source of halide. Thisfinding is advantageous because the pseudo-living polymers may beprepared in the absence of phosphorous-containing compounds, in theabsence of alkyl aluminoxane compounds, which are expensive, and withoutany particular need to prepare the catalyst by a specific process.

In another embodiment, where A contains an ester group, thefunctionalizing agents can be defined by the formulas (III) and (IV)

where R¹, R², and Z are as defined above, and R⁴ is a monovalent organicgroup, or, in the case where R² or R¹ combines with R⁴ to form a cyclicgroup, R⁴ may be a divalent organic group and R² may be a trivalentorganic group.

Non-limiting examples of ester groups include α,β-unsaturated esters,methacrylic acid esters, and acrylic acid esters.

The preferred ester-containing compounds include filler-interactivegroups, i.e., Z, that include N,N-disubstituted aminophenyl, imine,cyclic amino, isocyanate, isothiocyanate, and amide groups. Non-limitingexamples of these ester-containing functionalizing agents includetert-butyl 4-(N,N-dimethylamino)benzoate, tert-butyl4-(N,N-diethylamino)benzoate, bis(4-(N,N-diethylamino)benzyl maleate,tert-butyl 4-(1-hexamethyleneiminomethyl)benzoate,bis(4-(1-hexamethyleneiminomethyl)benzyl)maleate, tert-butyl4-isocyanatobenzoate, and bis (4-isocyanatobenzyl)maleate.

In another embodiment, where A contains an isocyanate or isothiocyanategroup, the functionalizing agents can be defined by the formula (V)E=C═N—R²—R¹—Z  (V)where R¹, R², and Z are as defined above, and where e is O or S.

Non-limiting examples of isocyanate groups include (2-isocyanato)ethyl,(3-isocyanato)propyl, (4-isocyanato)butyl, and (5-isocyanato)pentyl.Examples of isothiocyanate groups include the isothiocyanato equivalentsof the foregoing groups.

The preferred isocyanate or isothiocyanate-containing groups includefiller-interactive groups, i.e., Z, that include N,N-disubstitutedaminophenyl, cyclic amino, imine and amide groups. A non-limitingexample of an isocyanate-containing functionalizing agent definable bythe formula (V) includes4-(N,N-diethylamino)phenyl-4′-isocyantophenylmethane.

In another embodiment, where A contains an amide group, functionalizingagents of the present invention can be defined by the formulas (VI) and(VII)

where R¹, R², Z, and each R⁴, which may be the same or different, are asdefined above, and where R² may combine with any R⁴, or two R⁴ groupsmay combine to form a cyclic group. In this formula and all others inthis specification, R groups are defined by the types of groups they maycontain. It should be understood that, wherever two or more R groups ofthe same general type, i.e., R⁴, appear in a formula, those R groups maybe the same or different, within their general definition.

Non-limiting examples of reactive amide groups includeN-alkyl-isocyanulates, 3-(N,N-dialkylamido) propyl, trihydrocarbylisocyanulate, 3-(N,N-dihydrocarbylamido)alkyl, N-hydrocarbylcaprolactam,and N-hydrocarbylpyrrolidone groups.

One particularly preferred class of amide-containing functionalizingagents include those compounds where Z is an amide. Thesefunctionalizing agents have surprisingly been found to be extremelyuseful for functionalizing pseudo-living polymers that have beenprepared with lanthanide-based catalyst systems that employ trialkylaluminum, dialkyl aluminum hydride, alkyl aluminum hydride, or alkylaluminoxane alkylating agents or any combination of these, and a sourceof halide. This finding is advantageous because the pseudo-livingpolymers may be prepared in the absence of phosphorous-containingcompounds, and without any particular need to prepare the catalyst by aspecific process.

Some specific non-limiting examples of amide-containing functionalizingagents definable by the formulas (VI) or (VII) includeN-methylpyrrolidone, M ethylpyrrolidone, andN′,N-dimethylimidazolidinone (DMI).

The functionalized polymers are prepared by contacting one or more ofthe foregoing functionalizing agents, including mixtures thereof, with apseudo-living polymer. If a solvent is employed, it is preferable toemploy a solvent in which both the pseudo-living polymer and thefunctionalizing agent are soluble, or in which they may both besuspended. Preferably, this contacting takes place at a temperature ofless than 160° C., and more preferably at a temperature from about 20°C. to about 100° C. Further, the reaction time is preferably from about0.1 to about 10 hours, and more preferably from about 0.2 to about 5hours.

The amount of functionalizing agent used can vary. Preferably, fromabout 0.01 to about 200 moles of functionalizing agent per mole oflanthanide, and more preferably, from about 0.1 to about 150 moles permole of lanthanide are employed.

The reaction between the pseudo-living polymer and the functionalizingagent is quenched by using reagents such as, but not limited to,isopropyl alcohol, methanol, and water. Stabilizers, such as2,6-di-tert-butyl-4-methylphenol (BHT), can be added during or afterquenching.

Before quenching the resulting polymer, however, certain reactivecompounds can be added to provide additional functionality to thepolymer. These reactive compounds include those that will undergoaddition reactions with metal alkoxides or metal amides. Addition of aprotic quenching agent is believed to remove the metal via asubstitution reaction and thereby leave a lanthanide or aluminum aminogroup at the polymer chain end. A reaction between the metal amide andthe metal amide-reactive compound before quenching is believed toprovide additional functionality.

The polymer product can be recovered by using any technique that iscommonly employed in the art. For example, the polymer product can becoagulated in a hindered solvent such as isopropyl alcohol, and thendried in a hot air oven or hot mill. Alternatively, the polymer productcan be recovered by steam desolventization and successive hot air dryingor drying on a hot mill or the like. A processing oil can be added priorto finishing.

The resulting functionalized polymer can be represented by the formula(XV)

where R¹ and R³ are as defined above, and A* is the residue of the iminoportion of the functionalizing agent that has undergone an additionreaction with a pseudo-living polymer, and is polymer having a cismicrostructure that is greater than about 85%, a 1,2- or 3,4-unitcontent that is less than about 3%, and a molecular weight distributionthat is less than about 5. More preferably, the polymer has a cismicrostructure that is greater than about 90%, a 1,2- or 3,4-unitcontent that is less than about 2%, and a molecular weight distributionthat is less than about 4.

Polymers carrying alkoxysilane functionality may couple via acondensation reaction. For example, polymers represented by the formula(XV) may condense to form a coupled polymer that is represented by thefollowing formula (XVI)

where A*, R¹ and R⁴ are as defined above.

Reference to the functionalized polymers will likewise include thecondensation products thereof. In the event that any R⁴ is ORS, it maylikewise couple with another functionalized polymer. Advantageously, thecoupling of functionalized polymers where Z is a silane group improvesthe cold flow resistance of the polymers.

The functionalized polymers of this invention can advantageously be usedin the manufacture of various tire components including, but not limitedto, tire treads, side walls, subtreads, and bead fillers. They can beused as all or part of the elastomeric component of a tire stock. In oneembodiment, the functionalized polymers comprise greater than about 10percent by weight (pbw), more preferably, greater than about 20 pbw, andeven more preferably greater than about 30 pbw, of the elastomericcomponent of the tire stock. Addition of the functionalized polymers toa tire stock does not alter the type or amount of other ingredientstypically included within these vulcanizable compositions of matter.Accordingly, practice of this invention is not limited to any particularvulcanizable composition of matter or tire compounding stock.

Typically, tire stocks include an elastomeric component that is blendedwith reinforcing fillers and at least one vulcanizing agent.Accelerators, oils, waxes, fatty acids and processing aids are oftenincluded. Vulcanizable compositions of matter containing syntheticrubbers typically include antidegradants, processing oils, zinc oxide,optional tackifying resins, optional reinforcing resins, optionalpeptizers, and optional scorch inhibiting agents.

The functionalized polymers of this invention may be used in conjunctionwith other rubbers to form the elastomeric component of a tire stock.These other rubbers may include natural rubber, synthetic rubber, orboth. Examples of synthetic rubber include synthetic poly(isoprene),poly(styrene-co-butadiene), poly(butadiene),poly(styrene-co-butadiene-co-isoprene) and mixtures thereof.

Reinforcing fillers may include both organic and inorganic fillers.Organic fillers include, but are not limited to carbon black, andinorganic fillers include, but are not limited to, silica, alumina,aluminum hydroxide, and magnesium hydroxide. Reinforcing fillers aretypically employed in an amount from about 1 to about 100 parts byweight per 100 parts by weight rubber (phr), and preferably from about20 to about 80 parts by weight phr, and more preferably from about 40 toabout 80 parts by weight phr based on the total weight of allreinforcing fillers employed. Typically, when an inorganic filler isused, it is used in combination with organic fillers. In theseembodiments, the total amount of reinforcing filler will include fromabout 30 to about 99 parts by weight inorganic filler and 1 to about 70parts by weight organic filler, based on 100 parts by weight totalfiller. More preferably, the total filler will include from about 50 toabout 95 parts by weight inorganic filler and from about 5 to about 50parts by weight organic filler based on 100 parts by weight filler.

Carbon blacks may include any commonly available carbon black, but thosehaving a surface area (EMSA) of at least 20 m²/g, and more preferably atleast 35 m²/g up to 200 m²/g or higher, are preferred. Surface areavalues used in this application are those determined by ASTM test D-1765by using the cetyltrimethyl-ammonium bromide (CTAB) technique.

Silicas (silicon dioxide) are generally referred to as wet-process,hydrated silicas because they are produced by a chemical reaction inwater, and precipitated as ultrafine, spherical particles. Theseparticles strongly associate into aggregates that in turn combine lessstrongly into agglomerates. The surface area, as measured by the BETmethod, gives the best measure of the reinforcing character of differentsilicas. Useful silicas preferably have a surface area of about 32 toabout 400 m²/g, preferably about 100 to about 250 m²/g, and morepreferably about 150 to about 220 m²/g. The pH of the silica filler isgenerally about 5.5 to about 7 and preferably about 5.5 to about 6.8.Commercially available silicas include Hi-Sil™ 215, Hi-Sil™ 233, andHi-Sil™ 190 (PPG Industries; Pittsburgh, Pa.). Useful commercial gradesof different silicas are also available from other sources includingRhone Poulenc.

Typically, a coupling agent is added when silica is used. One couplingagent conventionally used is bis-[3 (triethoxysilyl)propyl]-tetrasulfide, which is commercially available under thetradename S169 (Degussa, Inc.; New York, N.Y.). Additional couplingagents may include bis(3-(triethoxysilyl)propyl)trisulfide,bis(3-(triethoxysilyl)propyl)disulfide, 3-mercaptopropyltriethoxysilane,bis(3-(trimethoxysilyl)propyl)tetrasulfide,bis(3-(trimethoxysilyl)propyl)trisulfide,bis(3-(trimethoxysilyl)propyl)disulfide,3-mercaptopropyltrimethoxysilane,3-(trimethoxysilyl)propyl)diethylthiocarbamyl tetrasulfide, and3-(trimethoxysilyl)propyl)benzothiazyl tetrasulfide. These agents aretypically employed in an amount from about 1 to about 20 phr, and morepreferably from about 3 to about 15 phr. Advantageously, less couplingagent is required when the functionalized polymers of this invention,which include a silane functionality, are employed.

Reinforced rubber compounds can be cured in a conventional manner withknown vulcanizing agents. For example, sulfur or peroxide-based curingsystems may be employed. For a general disclosure of suitablevulcanizing agents one can refer to Kirk-Othmer, ENCYCLOPEDIA OFCHEMICAL TECHNOLOGY, 3^(rd) Edition, Wiley Interscience, N.Y. 1982, Vol.20, pp. 365-468, particularly VULCANIZATION AGENTS AND AUXILIARYMATERIALS pp. 390-402, or Vulcanization by A. Y. Coran, ENCYCLOPEDIA OFPOLYMER SCIENCE AND ENGINEERING, 2^(nd) Edition, John Wiley & Sons,Inc., 1989. Vulcanizing agents may be used alone or in combination. Thisinvention does not appreciably affect cure times. Typically,vulcanization is effected by heating the vulcanizable composition; e.g.,it is heated to about 170° C. Cured or crosslinked polymers may bereferred to as vulcanizates.

Tire formulations are compounded by using mixing equipment andprocedures conventionally employed in the art. Preferably, an initialmasterbatch is prepared that includes the elastomer component and thereinforcing fillers, as well as other optional additives such asprocessing oil and antioxidants. The polyolefin additives are preferablyadded during preparation of the initial masterbatch. Once this initialmasterbatch is prepared, the vulcanizing agents are blended into thecomposition. The composition can then be processed into tire componentsaccording to ordinary tire manufacturing techniques including standardrubber curing techniques. Rubber compounding techniques and theadditives employed therein are generally known as disclose in TheCompounding and Vulcanization of Rubber, by Stevens in RUBBER TECHNOLOGYSECOND EDITION (1973 Van Nostrand Reihold Company). Pneumatic tires canbe made according to U.S. Pat. Nos. 5,866,171; 5,876,527; 5,931,211; and5,971,046, which are incorporated herein by reference.

The functionalized polymers of this invention can also be used in themanufacture of hoses, belts, shoe soles, window seals, other seals,vibration damping rubber, and other industrial products.

In order to demonstrate the practice of the present invention, thefollowing examples have been prepared and tested as described in theExamples Section disclosed hereinbelow. The examples should not,however, be viewed as limiting the scope of the invention. The claimswill serve to define the invention.

EXAMPLES Examples 1-4

A catalyst was prepared by mixing 0.5 g of 1,3-butadiene monomer inhexanes, 0.32 mmol of neodymium neodecanoate in hexanes, 31.7 mmol ofmethylaluminoxane in toluene, and 6.67 mmol of diisobutylaluminumhydride in hexanes within a dried and N₂ purged bottle equipped with arubber septum. After two minutes of contact, 1.27 mmol ofdiethylaluminum chloride in hexanes was added to the mixture. Themixture was then aged at room temperature for about 15 minutes.

Polybutadiene polymer was prepared by mixing the catalyst solutionprepared above with 611 g of 1,3-butadiene monomer in about 3,459 g ofhexanes at 25° C. within a two-gallon stainless steel reactor equippedwith an agitator and a jacket for temperature control. This mixture wasagitated for about 10 minutes at 24° C. The jacket temperature wasincreased to 72° C. and agitation continued for 33 minutes, after whichthe jacket temperature was lowered to 70° C. The polymer cement wassampled into separate dried and N₂-purged bottles and identified asExamples 1-4.

4,4′-bis(N,N-diethylamino)benzophenone (DEAB) was added as a toluenesolution to the respective samples in an amount and at a temperature asset forth in Table I. The functionalizing agent was allowed to react forthe time specified, quenched with a small amount of isopropyl alcoholand 2,6-di-t-butyl 4-methyl phenol (BHT) in hexanes, and then thepolymer was isolated by coagulation in isopropyl alcohol and successivedrum drying. Comparative Example 4 was determined to have a 93 percentcis structure by using FTIR analysis.

Table I sets forth the Mooney Viscosity (ML 1+4@100° C.), the Mooneyrelaxation to 20% torque (T-80), the number average molecular weight(M_(n)), the weight average molecular weight (M_(w)), and the molecularweight distribution as determined by GPC that was universally calibratedfor polybutadiene based on polystyrene. Bound rubber was measured byimmersing finely shredded uncured rubber specimens into toluene at roomtemperature. After 40 hours, the composition was filtered and boundrubber was calculated from the weight of the dried sample compared toother insoluble ingredients. Also, the samples were tested to determinetan δ at 50° C. (frequency at 31.4 rad/s and 3% strain).

The percent functionality of the polymer was obtained from the arearatios of UB and R¹ chromatograms and the number average molecularweight of the polymer (M_(n)) obtained by GPC by using universalcalibration for polystyrene and high cis butadiene based on polystyrenestandards. The following three assumptions were made: (1) the UVabsorbance of an end-functional group on a n-butyllithium (n-BuLi)initiated polymer was the same as the UV absorbance of theend-functional group on a lanthanide-catalyzed polymer, (2) n-BuLiinitiated polymers are 100% functionalized, and (3) the area ratio ofUV/RI is a linear function of the inverse of the M_(n) of the polymer.Pursuant to the method employed, a calibration curve of UV/RI area ratio(A) and M_(n) of polymers that were initiated with n-BuLi and terminatedwith the same imine compound was established according to the followingformula: A=a(1/M_(n))+b where A (BuLi,endgroup)=A_((BuLi, polymer))−A_((BuLi-backbone))=(a_((polymer))−a_((backbone)))(1/M_(n))+(b_((polymer))−b_((backbone))). Parameters a and b wereobtained by least square linear fitting of GPC data of n-BuLi initiatedand imine terminated polymers and n-BuLi initiated and alcoholterminated polymers, with 3 different molecular weights. The percentfunctionalities (F) of unknown polymers initiated by lanthanidecatalysts were obtained from GPC data of the functionalized, unknownpolymer and the corresponding unfunctionalized (base) polymer accordingto the following formula:F=A_((unknown, endgroup, M))/A_((BuLi, endgroup, M))=(A_((unknown, polymer, M))−A_((unknown, backbone, M)))/[(a_((polymer))−a_((backbone)))(1/M)+(b_((polymer))−b_((backbone)))].

Examples 5-7

A catalyst was prepared by mixing 0.5 g of 1,3-butadiene monomer inhexanes, 0.275 mmol of neodymium neodecanoate in hexanes, 27.5 mmol ofmethylaluminoxane in toluene, and 5.77 mmol of diisobutylaluminumhydride in hexanes within a dried and N₂ purged bottle equipped with arubber septum. After two minutes of contact, 1.10 mmol ofdiethylaluminum chloride in hexanes was added to the mixture. Themixture was then aged at room temperature for about 15 minutes.

Polybutadiene polymer was prepared as in Examples 1-4, except that thejacket temperature was initially set at 26° C., and was increased to 82°C. The polymer cement was sampled into separate dried and N₂-purgedbottles and identified as Examples 5-7. Examples 6 and 7 werefunctionalized with DEAB, which was charged to the bottles in toluenesolution, as set forth in Table I. Comparative Example 5 was notfunctionalized with DEAB.

Examples 8-10

A catalyst was prepared by mixing 0.5 g of 1,3-butadiene monomer inhexanes, 0.317 mmol of neodymium neodecanoate in hexanes, 31.7 mmol ofmethylaluminoxane in toluene, and 6.67 mmol of diisobutylaluminumhydride in hexanes within a dried and N₂ purged bottle equipped with arubber septum. After two minutes of contact, 1.27 mmol ofdiethylaluminum chloride in hexanes was added to the mixture. Themixture was then aged at room temperature for about 15 minutes.

Polybutadiene polymer was prepared as in Examples 1-4, except that thejacket temperature was initially set at 27° C., and was increased to 82°C. The polymer cement was sampled into separate dried and N₂-purgedbottles and identified as Examples 8-10. Examples 9 and 10 werefunctionalized with DMI, which was charged to the bottles in neat form,as set forth in Table I. Comparative Example 8 was not functionalizedwith DMI.

TABLE I 1 2 3 4 5 6 7 8 9 10 Functionalizing Agent None DEAB DEAB NoneNone DEAB DEAB None DMI DMI Amount of functionalizing — 25 50 — — 25 50— 25 50 agent (eq/Nd) Reaction Temp (° C.) — 50 50 — — 50 50 — 50 50Reaction Time (min) — 180 180 — — 180 180 — 180 180 ML1 + 4 @ 100° C.26.6 30.3 29.5 28.7 44.1 48.4 47.0 32 35.7 34.2 T-80 (s) 3.3 3.3 3.3 3.74.0 3.7 4.0 3.3 3.7 3.7 Mn (kg/mol) 121 123 123 121 140 139 144 122 122124 Mw (kg/mol) 235 238 237 237 274 279 279 240 246 245 Mw/Mn 1.9 1.91.9 1.9 2.0 2.0 1.9 2.0 2.0 2.0 % functionality 0.0 64 68 0 0 58 67 0n/a n/a

Examples 11-18

Certain of the resulting polymers were individually compounded intorubber formulations with either silica (Nipsil VN3™; Nippon Silica;Japan) or carbon black (N339) as a filler. Namely, an initialmasterbatch was blended within an internal mixer at an initialtemperature of about 110° C. for about 3.5 minutes. The masterbatch wasallowed to cool and then re-milled within the same internal mixer forabout 2 minutes. Then, a cure system was added while the compound wascontinually processed within the internal mixer at a temperature ofabout 80° C. for about 1 minute. The compounding recipes that wereemployed are set forth in Tables II and III.

TABLE II COMPOUNDING RECIPE WITH SILICA Ingredient Parts per HundredRubber Elastomer 100 Aromatic Oil 10 Silica 50 Stearic Acid 2Antioxidant 1 Masterbatch Total 163 Zinc Oxide 2.5 Sulfur .03Accelerators 2.5 Total 171.5

TABLE III COMPOUNDING RECIPE WITH CARBON BLACK Ingredient Parts perHundred Rubber Elastomer 100 Aromatic Oil 10 Paraffin Oil 1.5 CarbonBlack 50 Stearic Acid 2 Antioxidant 1 Masterbatch Total 164.5 Zinc Oxide2 Sulfur 1.3 Accelerators 1.2 Total 169.0

Once compounded, each formulation was press cured at about 145° C. forabout 33 minutes. The cured samples were then analyzed to determinetensile strength at break and elongation at break according toJIS-K6301. Also, the samples were tested to determine tan δ and G′ at50° C. (frequency at 31.4 rad/s and 3% strain), as well as Lambournewear.

The results of testing the vulcanizates filled with carbon black are setforth in Table N, and the results of testing the vulcanizates filledwith silica are set forth in Table V. The data in Table IV, except forMooney Viscosity (ML1+4@100° C.), has been indexed to the vulcanizatesprepared by using polymer Sample 1, and the data in Table V, except forMooney Viscosity, has been indexed to the vulcanizates prepared by usingpolymer Sample 8. The polymer sample labeled A is a weighted averagebetween sample polymers 1 and 11 calculated to provide Mooney Viscosity(ML1+4@100° C.) of about 44.

TABLE IV Polymer No 1 4 A (aproximation from 1 and 11) 7 8 9 11 Agentnone DEAB none DEAB none DMI none Amount (eq/Nd) — 50 — 50 — 25 — RawMV26.6 29.5 44.1 47 32.3 35.7 54.6 Raw T-80 3.3 3.3 4 4 3.3 3.7 4 CompoundMooney 46.4 62.5 69.65 81.4 51.3 54.7 83.6 Bound Rubber (index) 100 275113 254 101 99 121 M300 (RT) (index) 100 111 110 112 101 106 116 Tb (RT)(index) 100 116 108 109 110 101 112 Eb (RT) (index) 100 104 98 95 105 9696 M300 (100 C.) (index) 100 102 108 117 108 112 113 Tb (100 C.) (index)100 104 101 107 106 116 101 Eb (100 C.) (index) 100 100 94 92 99 104 913% tanδ @50 C. 100 78 91 75 103 97 86 (index, smaller is better)

TABLE V Polymer # 8 10 1 3 Agent none DMI none DEAB Amount (eq) — 50 —25 RawMV 32.3 34.2 26.6 30.3 Raw T-80 3.3 3.7 3.3 3.3 Compound Mooney115.1 118.0 110.5 120.4 Bound Rubber (index) 100 113 98 117 M300 (RT)(index) 100 94 86 94 Tb (RT) (index) 100 100 95 111 Eb (RT) (index) 100104 106 109 M300 (100 C.) (index) 100 98 84 92 Tb (100 C.) (index) 100107 90 107 Eb (100 C.) (index) 100 108 109 115 G′ @10% -G′ @3% (smalleris better) 100 68 102 82

Various modifications and alterations that do not depart from the scopeand spirit of this invention will become apparent to those skilled inthe art. This invention is not to be duly limited to the illustrativeembodiments set forth herein.

1. A method for preparing a functionalized polymer comprising the steps of: preparing a pseudo-living polymer by polymerizing conjugated diene monomer with a lanthanide-based catalyst, wherein the lanthanide-based catalyst comprises (a) a lanthanide compound, (b) an alkyl aluminoxane, and (c) a source of halogen; and reacting the pseudo-living polymer with at least one functionalizing agent selected from the group consisting of:

where R¹ is a divalent bond or divalent organic group comprising from 0 to about 20 carbon atoms, R² is a divalent organic group or trivalent organic group in the case where R² combines with R⁴ to form a cyclic group, each R⁴ is independently a hydrogen atom, a monovalent organic group, or, in the case where R⁴ combines with R¹, R², or another R⁴, R⁴ may be a divalent organic group, and Z is selected from the group consisting of N,N-disubstituted aminophenyl groups, cyclic amino groups, imine groups, amide groups, isocyanate groups, isothiocyanate groups, and epoxy groups, with the proviso that R¹, R², R⁴ and Z are substituents that will not protonate a pseudo-living polymer.
 2. The method of claim 1, where Z is an amide.
 3. The method of claim 2, wherein the pseudo-living polymer is prepared in the absence of phosphorus-containing compounds.
 4. The method of claim 2, wherein (b) comprises an alkyl aluminoxane or a mixture of an alkyl aluminoxane and a trialkylaluminum, dialkylaluminum hydride, or alkylaluminum dihydride.
 5. The method of claim 1, where the functionalizing agent is selected from the group consisting of N-alkyl-isocyanulates, 3-(N,N-dialkylamido) propyl, trihydrocarbyl isocyanulate, 3-(N,N-dihydrocarbylamido)alkyl, N-hydrocarbylcaprolactam, and N-hydrocarbylpyrrolidone groups.
 6. The method of claim 1, wherein the lanthanide-based catalyst comprises (a) neodymium neodecanoate; (b) methylaluminoxane and diisobutylaluminum hydride; and (c) diethylaluminum chloride.
 7. The method of claim 1, wherein the conjugated diene monomer is 1,3-butadiene. 